Fuel supply devices for cold starting of internal combustion engines

ABSTRACT

A fuel supply device for supplying fuel to provide a coldstarting mixture in an internal combustion engine in which fuel is expelled from a chamber into the engine induction system by movement of a movable wall of the chamber which movement is caused by means dependent on the initiation of an engine-starting operation, the volume of the chamber being controlled by thermostatic means dependent on engine temperature so that the quantity of fuel available is greater when the engine temperature at starting is lower. Fuel is fed automatically into the chamber as its volume increases due to fall of temperature, and the outlet from the chamber is closed by a valve when its volume is reduced to a minimum.

United States Patent Inventor Gray E. D. Ross Trlng, England Appl. No 882,871 Filed Dec. 8, I969 Patented Nov. I6, 1971 Assignee The Zenith Carburetter Company Limited Stanmore, Mlddlesex, England Priority Dec. 17, 1968 Great Britain 59,964/68 FUEL SUPPLY DEVICES FOR COLD STARTING OF INTERNAL COMBUSTION ENGINES [56] References Cited UNITED STATES PATENTS 2.092.685 9/l937 Viel v. 123/] 8775 2.89l,70l 6/l959 Downing et al.. l23/l39.ll A 2.984.228 5/l96l Brawn et al l23/l39.|7

Primary Examiner- Laurence M. Goodridge Attorney-Stevens, Davis. Miller & Mosher ABSTRACT: A fuel supply device for supplying fuel to provide a cold-starting mixture in an internal combustion engine in which fuel is expelled from a chamber into the engine induction system by movement of a movable wall of the chamber which movement is caused by means dependent on the initiation of an engine-starting operation, the volume of the chamber being controlled by thermostatic means dependent on engine temperature so that the quantity of fuel available is greater when the engine temperature at starting is lower Fuel is fed automatically into the chamber as its volume increases due to fall of temperature. and the outlet from the chamber is closed by a valve when its volume is reduced to a minimum.

FUEL SUPPLY DEVICES FOR COLD STARTING OF INTERNAL COMBUSTION ENGINES This invention relates to fuel supply devices for supplying fuel to internal combustion engines for starting such engines from cold.

It is known that the successful starting of a petrol engine under cold conditions requires, firstly, the delivery to the induction manifold of a quantity of fuel sufi'icient to provide the initial mixture of petrol and air which will start the engine running, and secondly, the provision of enrichment of the mixture of fuel and air drawn from the carburetor, while the engine is warming up, until the engine reaches its nonnal temperature.

It is the object of the present invention to provide a fuel supply device which is arranged to supply a predetermined fixed quantity of fuel to the engine during an actual starting operation.

According to the invention, a fuel supply device for supplying fuel to an internal combustion engine for starting the engine from cold comprises a chamber bounded on one side by a movable wall, thermostatically controlled means acting on said movable wall to permit enlargement of the volume of said chamber with decrease of temperature, means to supply fuel to said chamber automatically as its volume increases, through a nonretum valve, passage means to connect said chamber to the induction system of an engine, means dependent on the initiation of an engine starting operation to produce a thrust on said movable wall acting to move it so as to reduce the volume of said chamber and expel fuel therefrom into the engine induction system, and valve meansacting to close said passage means when said movable wall, during its fuel-expelling movement, reaches a predetermined position.

The rate of flow of fuel from said chamber to the engine induction system may be determined by a control orifice in said passage means, and a profiled needle, carried by the movable wall, may cooperate with said orifice to vary the rate of flow as One embodiment of the invention will now be described, by

way of example, with reference to the accompanying drawing which shows a sectional view of the fuel supply device and diagrammatic representation of associated components.

Referring to the drawing, the float chamber of a carburetor which supplies fuel to the engine for normal running is shown at 10 (the other parts of the carburetor being omitted from the drawing), and is supplied with fuel through a conduit 11 from a fuel pump indicated diagrammatically at 12 and drawing fuel from a fuel tank 13. The fuel supply device comprises a housing 14 defining a cavity divided into two chambers 15 and 16 by a movable wall in the form of a flexible diaphragm 17 the peripheral edge of which is clamped between two components forming the housing 14, the central part of the diaphragm 17 being clamped between two rigid discs 18. The diaphragm 17 is biassed by a light spring 19 in a direction to increase the volume of the chamber 15 and reduce the volume of the chamber 16. A stem 21 extending through the diaphragm l7 and discs 18, and clamped to them by a nut 22, extends through the chamber 16, through a flexible diaphragm 23 sealing the said chamber 16, and through a guide 24, to cooperate with a stop 25 on a lever 26, pivoted at a fixed point at 27 and connected to a temperature sensitive device 28 which, with decreasing temperature, acts to pivot the lever 26 in a direction to allow the diaphragm 17 to move in the direction in which it is urged by the spring 19. The temperature sensitive device 28 may be of any suitable form, such as a bimetallic element.

A passage 29, in which is mounted a nonretum valve 31, connects the chamber 15 to the float chamber 10, and an orifice 32 in the center of the wall of the chamber 15 leads to a conduit 33 connected, through a nonretum valve 34, to the induction system of an internal combustion engine with which the fuel supply device is used, a part of the induction system, assumed to be between the usual throttle valve and the inlets to the engine cylinders, being shown diagrammatically at 35.

The stem 21, on the side of the diaphragm 17 facing the chamber 15, is formed as or carries coaxially therewith, a profiled needle 36 projecting into the orifice 32 so that the effective area of the orifice varies with the position of the diaphragm 17, and, mounted on the stem 21 on that side of the diaphragm 17 is a resilient sealing member 37 including a conical portion 38 adapted to enter and close the orifice 32, and a lip 39 adapted to engage the wall of the chamber 15 around the orifice 32 to provide a double seal for the orifice when the diaphragm has approached within a predetermined distance of the wall of the chamber 15 in which the orifice 32 is formed.

The chamber 16 is connected by a conduit 41 to the conduit 1 1.

When the vehicle engine is running the fuel pump generates pressure which acts in the chamber 16 to hold the diaphragm 17 in a position in which the orifice 32 is closed by the sealing member 37, and, once the engine has warmed up to at or near its working temperature, the stop 25 engages the stem 2] with the diaphragm in this position. No fuel therefore flows from the chamber 15 into the induction system. When the engine is stopped, the fuel pressure no longer supports the diaphragm, but displacement of the diaphragm 17 to increase the volume of the chamber 15 is controlled by the temperature-sensitive device 28 in response to cooling of the engine and, as the engine cools, fuel is drawn into the chamber 15 and fuel is displaced from the chamber 16. When, after it has cooled, the engine is restarted, the fuel pump creates pressure in the chamber 16 to displace the diaphragm l7 and force fuel from the chamber 15 into the induction system so as to provide a suitable cold-starting mixture, the quantity of fuel supplied depending on the volume change of the chamber 15 and the rate of supply depending on the effective area of the orifice 32. Once the sealing member 37 has seated, no further fuel can be supplied from the chamber 15 until the engine is stopped and restarted.

The volume of fuel supplied from the chamber 15 can be adjusted, for example by adjusting the angular travel of the lever 26, and the rate of delivery can be adjusted by varying the size of the orifice 32 or the needle 36, or both. The profile of the needle 36 may be selected to give any desired variation of the rate of delivery during the stroke of the diaphragm l7.

Advantages of the device according to the present invention are:

i. that very rapid delivery of fuel to the induction system is effected as soon as cranking of the engine is initiated.

2. The delivery of fuel is neither dependent upon, nor related to, the air pressure in the induction system.

3. The volume of fuel delivered can be controlled.

4. The rate of delivery of fuel can be controlled and can be variable during the time of delivery.

5. Only one charge of fuel is supplied even if repeated attempts are made to start the engine in quick succession, because the chamber 15 cannot recharge until the fuel pressure in chamber 16 falls. Thus the building up of an excessive charge of fuel in the induction system is avoided.

The device according to the invention may be used, with a supply of suitable fuel, for the priming of compression-ignition engines.

I claim:

1. A fuel supply device for supplying fuel to an internal combustion engine for starting the engine from cold, compris ing a fuel chamber bounded on one side by a movable wall biassing means acting on said movable wall to provide a continuously acting force tending to enlarge the volume of said fuel chamber, stop means opposing movement of said mova- .ble wall by said biassing means, thermostatically controlled means operative to adjust the position of said stop means so as to pennit movement of said movable wall by said biassing means with decrease of temperature to enlarge the volume of said fuel chamber, means to supply fuel to said chamber automatically as its volume increases, through a nonretum valve, passage means to connect said chamber to the induction system of an engine, means dependent on the initiation of an engine starting operation to produce a thrust on said movable wall acting to move it so as to reduce the volume of said chamber and expel fuel therefrom into the engine induction system, and valve means operated by movement of said movable wall and acting to close said passage means when said movable wall, during its fuel-expelling movement, reaches a predetermined position.

2. A fuel supply device according to claim I, wherein a control orifice is provided in the passage means which connect the said chamber to the engine induction system to control the rate of flow of fuel from said chamber.

3. A fuel supply device according to claim 2, wherein a profiled needle carried by the movable wall, cooperates with the control orifice to vary the rate of flow of fuel through the control orifice as the movable wall moves.

4. A fuel supply device according to claim 1, wherein the movable wall separates the said chamber from a second chamber adapted to be connected to the engine fuel supply system on the downstream side of the fuel pump of said system so that the pressure of fuel delivered by the fuel pump provides the thrust to move the movable wall.

5. A fuel supply device according to claim 1, wherein the movable wall is a flexible diaphragm.

6. A fuel supply system according to claim 1, wherein the valve means acting to close said passage means comprise a resilient-sealing member carried by the movable wall and including a conical portion adapted to enter and close the end of said passage means opening into the chamber from which said passage means lead, and a lip to engage the wall of said chamber around said end of the passage means.

7. A fuel supply system according to claim 1, wherein a rod extending through and fixed to the movable wall cooperates with a stop the position of which is determined by the thermostatically controlled means.

8. A fuel supply device according to claim 7, wherein a profiled needle is carried by the rod and cooperates with a control orifice in the passage means which connects said fuel chamber to the engine induction system to vary the rate of flow of fuel through the control orifice as the movable wall moves.

9. A fuel supply system according to claim 6 wherein the resilient sealing member is mounted on a rod extending through and fixed to the movable wall.

I I I t i 

1. A fuel supply device for supplying fuel to an internal combustion engine for starting the engine from cold, comprising a fuel chamber bounded on one side by a movable wall biassing means acting on said movable wall to provide a continuously acting force tending to enlarge the volume of said fuel chamber, stop means opposing movement of said movable wall by said biassing means, thermostatically controlled means operative to adjust the position of said stop means so as to permit movement of said movable wall by said biassing means with decrease of temperature to enlarge the volume of said fuel chamber, means to supply fuel to said chamber automatically as its volume increases, through a nonreturn valve, passage means to connect said chamber to the induction system of an engine, means dependent on the initiation of an engine starting operation to produce a thrust on said movable wall acting to move it so as to reduce the volume of said chamber and expel fuel therefrom into the engine induction system, and valve means operated by movement of said movable wall and acting to close said passage means when said movable wall, during its fuel-expelling movement, reaches a predetermined position.
 2. A fuel supply device according to claim 1, wherein a control orifice is provided in the passage means which connect the said chamber to the engine induction system to control the rate of flow of fuel from said chamber.
 3. A fuel supply device according to claim 2, wherein a profiled needle carried by the movable wall, cooperates with the control orifice to vary the rate of flow of fuel through the control orifice as the movable wall moves.
 4. A fuel supply device according to claim 1, wherein the movable wall separates the said chamber from a second chamber adapted to be connected to the engine fuel supply system on the downstream side of the fuel pump of said system so that the pressure of fuel delivered by the fuel pump provides the thrust to move the movable wall.
 5. A fuel supply device according to claim 1, wherein the movable wall is a flexible diaphragm.
 6. A fuel supply system according to claim 1, wherein the valve means acting to close said passage means comprise a resilient-sealing member carried by the movable wall and including a conical portion adapted to enter and close the end of said passage means opening into the chamber from which said passage means lead, and a lip to engage the wall of said chamber around said end of the passage means.
 7. A fuel supply system according to claim 1, wherein a rod extending through and fixed to the movable wall cooperates with a stop the position of which is determined by the thermostatically controlled means.
 8. A fuel supply device according to claim 7, wherein a profiled needle is carried by the rod and cooperates with a control orifice in the passage means which connects said fuel chamber to the engine induction system to vary the rate of flow of fuel through the control orifice as the movable wall moves.
 9. A fuel supply system according to claim 6 wherein the resIlient sealing member is mounted on a rod extending through and fixed to the movable wall. 